Gas turbine engines operate to produce mechanical work or thrust. Specifically, land-based gas turbine engines typically have a generator coupled thereto for the purposes of generating electricity. A gas turbine engine comprises an inlet that directs air to a compressor section, which has stages of rotating compressor blades. As the air passes through the compressor, the pressure of the air increases. The compressed air is then directed into one or more combustors where fuel is injected into the compressed air and the mixture is ignited. The hot combustion gases are then directed from the combustion section to a turbine section by a transition duct. The hot combustion gases cause the stages of the turbine to rotate, which in turn, causes the compressor to rotate.
The hot combustion gases are directed through a turbine section by turbine blades and vanes. Stationary turbine vanes precede each stage of rotating blades in order to direct the flow of hot combustion gases onto the blades at the appropriate angle to maximize turbine efficiency. These blades and vanes are subject to extremely high operating temperatures, stresses, and strains. The blades may include one or more cooling passages formed below the surface for the passage of cooling air. Nonetheless, gas turbine blades in particular, may experience degradation, such as wear, nicks, dents, and corrosion. Some degradation may be repairable which presents a viable alternative to the high-replacement costs of blades. Blade repairs vary depending on the blade configuration but repairs are generally directed to blade tips or tip shrouds, typically using a weld overlay process. Blade repair techniques continue to be improved to provide a repaired replacement part that functions just as well as a new part.